The present invention relates to controlled trajectory drilling fittings. Adapted to be placed at the end of a drill-string. With the fitting making it possible to control, in real time, the variations of direction and of inclination of the drill-hole. In addition to controlling the azimuth, and the radius of curvature accurately, to reduce the friction phenomena and to limit the risks of jamming without requiring the fitting being raised to the surface.
The fitting of the present invention comprises a drill tool placed at its lower end, a motor for rotating the tool and at least one variable geometry stabilizer.
The fitting of the present invention may comprise another stabilizer and/or an elbow element.
The elbow element may be with fixed angle or variable angle and may be integrated with the motor.
By elbow element is meant a member introducing or capable of introducing locally, if not at a point, a discontinuity in the direction of the axis of the drillstring. That is to say that the axis of the drilling fitting is a crooked line at the level of the elbow element.
The variable geometry stabilizer may comprise means adapted for varying the distance between the axis of the fitting and the bearing surface of at least one blade of the stabilizer and/or means adapted for varying, at least axially, the position of the bearing surface of at least one blade of the stabilizer.
The fitting of the present invention may comprise at least one stabilizer which is interlocked for rotation with the tool.
The fitting of the present invention may comprise at least one stabilizer fast for rotation with the body of the motor.
The variable geometry stabilizer or stabilizers may be remote controlled if required from the surface.
The fitting of the present invention may include a variable geometry stabilizer as well as two other stabilizers placed on each side of said variable geometry stabilizer. The elbow element may be integrated with the motor.
The present invention relates to the use of one of the above described fittings at the end of a drill-string which may be driven in rotation by drive means situated on the surface.
Of course, the fitting of the present invention may provide control of the azimuth (of the direction of the drill hole), which may be facilitated by an elbow element integrated in the downhole motor, no rotation being applied to the drill-string from the surface.
Control of the radius of curvature is facilitated by the association of an elbow and a stabilizer.